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Capacitance - The Farad, The Unit Of Capacitance, Energy Storage In Capacitors, Capacitance And Alternating Current - Working voltage, The significance of capacitance

electrical charge circuit electric

Capacitance is an electrical effect that opposes change in voltage between conducting surfaces separated by an insulator. Capacitance stores electrical energy when electrons are attracted to nearby but separate surfaces. The voltage across an unchanging capacitance value will stay constant unless the quantity of charge stored is changed.

If the voltage across a capacitor is increased until charges jump from one plate to the other, the capacitor will probably fail, either momentarily or permanently. Capacitors are rated to specify the maximum continuous voltage that can be applied across the dielectric before the capacitor will fail.

Capacitance, inductance, and resistance are the passive electrical properties affecting electrical circuits. Understanding capacitance is an essential part of the study of electricity and electronics.



Asimov, Isaac. Understanding Physics: Light, Magnetism, and Electricity. Vol. II. Signet Books, The New American Library.

Bord, Donald J., and Vern J. Ostdiek. Inquiry Into Physics. 3rd ed. West Publishing Company, 1995.

Sear, Zemansky, and Young. College Physics. 6th ed. Addison-Wesley Publishing Company, 1985.

Donald Beaty


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Alternating current

—Electric current that flows first in one direction, then in the other; abbreviated AC.

Direct current (DC)

—Electrical current that always flows in the same direction.

Electric field

—The concept used to describe how one electric charge exerts force on another, distant electric charge.


—A negatively charged particle, ordinarily occurring as part of an atom. The atom's electrons form a sort of cloud about the nucleus.


—The unit of capacitance, equal to 1 Volt per Coulomb.


—No net charge, when positive and negative charges cancel.

Open circuit

—A physical break in a circuit path that stops the current.


—Possible asymmetrical charge distribution in a molecule.

Power supply

—A source of electrical energy used to supply a circuit.


—The positively-charged particle in atoms.

Short circuit

—Unwanted bypass of the expected current path in a circuit.


—Ratio of electrical potential energy to the quantity of charge.

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